Rslogix 500 missing ons command

Hi everyone,

today i was asked to look at a slc500 program. the programmer was unable to add a oneshot command to the program, the command is grayed out, the only option we have is the osr command. i tried my laptop and the same thing, even when i create a new program. We are using Rslogix 500 version 11.00.00 CPR9. in all my years, i have never run across this issue before.
Any one else had this issue and a solution?
just wanted your input before calling tech support tomorrow.
thanks in advance,
james

I have found that not all functions are available in all Firmware Revisions or Processors
it depends on the processor and the revision

GaryS,
i agree, but when i create a totally new project with a 5/05 64 k memory and an os of version 10 or later, you would expect the one shot command to be available, but it's not there. the command is grayed out.
james

The "ONS" instruction is not available on the SLC500 series of controllers. Only the "OSR"
which acts the same as the "ONS".

The "ONS" is available in the Micrologix series of controllers. Along with the "OSR" and "OSF" (they have all three)

See PDF's

https://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1747-rm001_-en-p.pdf

https://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1763-rm001_-en-p.pdf

Mickey,
thanks for the reply, working with so many versions of plc's can be a pain at times.
By chance would you know where in the manuals it states that the maximum number of series contacts in a rung is 18 and the number of parallel branches is limited to 8 in regards to the slc500 plc?
we have a program rung that takes 3 15" screens to display- the guy in my opinion was a nut, you cannot debug the rung it's so big. i want to shw management so we can modify the program.
thanks again,
james

James,


First (unfortunately) the limit of how many instructions a rung can have is limited by the PLC memory. It is theoretical to program a machine using one rung if the number of outputs fit in the nested branch limit.



The branch limit is Nested Branches, and I seem to remember 6 for the SLC . A Parallel Branch, that continues with NXB's, can be either unlimited or up in the hundreds. To nest a branch there will be a BST/BND inside a branch, then more BST's to max it out.


What I do for long rungs like you encountered is break it into sections, put each section on its own rung and set a bit, then the next section start with XIC my first bit, let that section set another bit.

Also I put all compares on a rung with a bit to show if it is true, then on the processing rung XIC that bit.
This is also good for troubleshooting as instead of looking at the output of a large rung and trying to see where it goes false is easier section by section.

I_Automation said:

The branch limit is Nested Branches, and I seem to remember 6 for the SLC . A Parallel Branch, that continues with NXB's, can be either unlimited or up in the hundreds.

Click to expand...

See this thread. Specifically post 11 which has a screencap of the RSLogix 500 help file (I don't have the software to hand myself atm or I'd just post my own).

"Nested branches are limited to a maximum of 4." "Parallel branches are limited to a maximum of 75."

James Mcquade said:

Mickey,
thanks for the reply, working with so many versions of plc's can be a pain at times.
we have a program rung that takes 3 15" screens to display- the guy in my opinion was a nut, you cannot debug the rung it's so big.
james

Click to expand...

I have seen similar done in programs we have here, that were programmed by reputable machine building company. A rung filled with a bunch of XICs and XIOs in series that just wraps and wraps all the way down the screen. Have to use the vertical scroll bar to see the full rung of logic.

plvlce said:

See this thread. Specifically post 11 which has a screencap of the RSLogix 500 help file (I don't have the software to hand myself atm or I'd just post my own).

"Nested branches are limited to a maximum of 4." "Parallel branches are limited to a maximum of 75."

Click to expand...

I had to open RSL500 [v12.00] to test my memory. (it's getting as bad as my legs I see)



Each rung max's out at:
128 instructions
4 nested branches
75 parallel branches